As far as SovStars goes, I am working on a "meatier" revision to the game-- however, it prolly won't ever be more than a hefty board game (more involved than checkers, less so than F&E...). For something truly flexible, with options for RPG integration and true conversion between the strategic and tactical levels, might I suggest you take a look at Victory By Any Means (VBAM)?

In addition to sounding like what you are looking for, it has the added benefit of a soon-to-be-released Starmada tie-in product...